1. Field of the Invention
The present invention relates to a centrifugal pump for handling liquefied gases and very low temperature fluids. More specifically, the present invention relates to a centrifugal pump including a pump with an impeller, and a motor for driving the impeller.
2. Description of the Related Art
Specialized pumps exist for handling low temperature fluids such as liquefied natural gas, liquefied petroleum gas, and other liquified gases. In general, these pumps each include a pump portion and a motor portion. The pump portion includes an impeller which imparts speedy motion to the fluid. The motor includes an electric motor which operates the impeller.
Since the operating temperatures for these specialized pumps are very low, it is necessary to adequately insulate the inside and outside of the pump and take other steps to minimize heating effects. For this reason, an insulating jacket typically surrounds these specialized pumps in an attempt to provide adequate heat insulation. Many of these insulating jackets operate ineffectively as well as detrimentally increase the size of the pump.
To assist heat insulation, it is preferable to have a pump with a small surface area. When starting the pump, it is necessary to have adequate cooling of the pump temperature so that the low temperature fluid does not inappropriately volatilize. Thus, a pump with a small heat capacity is needed for speedy cooling. The known pumps have high heat capacity and therefore provide ineffective and slow cooling prior to operation.
It is an object of the present invention to provide a pump which overcomes the drawbacks of the related art noted above.
It is another object of the present invention to provide an efficient centrifugal pump.
It is another object of the present invention to provide a pump which easily handles very low temperature fluids.
It is another object of the present invention to provide a pump which includes adequate heat insulation and has a small heat capacity.
It is another object of the present invention to provide a pump with a speedy start up.
The present invention relates to a centrifugal pump including a motor portion and a pump portion. The motor portion, which is coaxial with the pump portion, drives an impeller to pump a low temperature fluid. A pot is sealed to the pump portion to receive the low temperature fluid. The low temperature fluid contacts only the pump portion in the pot to thereby reduce the overall heat capacity of the centrifugal pump and thus reduce start time. A heat insulating jacket is in tight contact with the motor portion. A vent pipe extends from the pot, through the pump portion and within the heat insulating jacket, to a rear of the motor portion to increase safety and provide double-insulation to the vent pipe. The heat insulating jacket reduces the size and surface area of the centrifugal pump to resist heat flow and increase safety.
According to an embodiment of the present invention there is provided a centrifugal pump, for pumping a low temperature fluid, comprising: a pump portion, a motor portion on the pump portion, the pump portion including an impeller having a first rotation axis, the motor portion including a motor having a second rotation axis, the first rotation axis in coaxial alignment with the second rotation axis, the motor driving the impeller during an operation of the centrifugal pump to drive the pump portion and pump the low temperature fluid, insulating jacket means for thermally insulating at least the motor portion, the insulating jacket means surrounding at least the motor portion, at least a first vacuum jacket in the insulating jacket means, and the first vacuum jacket including at least a low pressure vacuum between a motor outer surface and an inner surface of the first vacuum jacket, whereby tight contact between the insulating jacket means and the motor portion and the coaxial alignment provides increased thermal efficiency, reduced size, and simplified construction.
According to another embodiment of the present invention there is provided a centrifugal pump, further comprising: a pot, the pot sealed around a lower portion of the pump portion, the pot solely receiving the low temperature fluid during the operation, an intake pipe in the lower portion extending away the pump portion along the first rotation axis into the pot, the intake pipe and the impeller in fluid communication, and the intake pipe and the impeller transporting the low temperature fluid from the pot during the operation, thereby restricting direct contact of the low temperature fluid to the pump portion and providing a reduced pump surface area with an improved startability.
According to another embodiment of the present invention there is provided a centrifugal pump, further comprising: a flow straightening plate, the flow straightening plate in the pot opposite the intake pipe, and the flow straightening plate having a shape preventing formation of a rotational flow of the low temperature fluid in the pot during the operation.
According to another embodiment of the present invention there is provided a centrifugal pump, further comprising: a release pipe, the release pipe in sealed communication between the motor portion and an external portion of the centrifugal pump, and the release pipe providing an easy release of any the low temperature fluid and a vapor of the low temperature fluid which has improperly entered the motor portion, thereby increasing reliability of the centrifugal pump.
According to another embodiment of the present invention there is provided a centrifugal pump, further comprising: a vent pipe, the vent pipe in vapor communication between the pot and the release pipe, and at least a first portion of the vent pipe within the first vacuum jacket, whereby the first vacuum jacket provides easy double-service thermal insulation of the motor portion and the vent pipe to reduce size while increasing safety.
According to another embodiment of the present invention there is provided a centrifugal pump, wherein: the release pipe extends from a rear side of the motor portion away from the first vacuum jacket.
According to another embodiment of the present invention there is provided a centrifugal pump, wherein: the at least a first portion of the vent pipe includes the entire vent pipe, whereby the first vacuum jacket provides easy double-insulation of the motor portion and the entire vent pipe while reducing size and increasing safety.
According to another embodiment of the present invention there is provided a centrifugal pump, wherein: at least the first portion of the vent pipe is greater that one half of an overall length of the vent pipe, whereby the first vacuum jacket provides easy double-insulation of the motor portion and the first portion while reducing size and increasing safety.
According to another embodiment of the present invention there is provided a centrifugal pump, wherein: the flow straightening plate includes at least a first and a second plate extending away from a bottom of the pot toward the intake pipe, and the first and the second plates perpendicular to each other.
According to another embodiment of the present invention there is provided a centrifugal pump, further comprising: a front end partitioning wall between the motor portion and the pump portion, a rear end partitioning wall on the motor portion opposite the front end partitioning wall, and the motor portion sealed between the front end partitioning wall and the rear end partitioning wall thereby separating the motor portion from the first vacuum jacket and allowing easy creation of the first vacuum jacket.
According to another embodiment of the present invention there is provided a centrifugal pump, wherein: the release pipe is in sealed communication between the rear end partitioning wall on motor portion and an external portion of the centrifugal pump.
According to another embodiment of the present invention there is provided a centrifugal pump, further comprising: at least a second vacuum jacket in the insulating jacket means, and the second vacuum jacket including at least a low pressure vacuum between a pot outer surface and an inner surface of the second vacuum jacket, whereby tight contact between the insulating jacket means and the pot and coaxial alignment provides increased thermal efficiency, smaller size, and simplified construction.
According to another embodiment of the present invention there is provided a centrifugal pump, for pumping a low temperature fluid, comprising: a pump portion, a motor portion on the pump portion, the pump portion including an impeller having a first rotation axis, the motor portion including a motor having a second rotation axis, the motor driving the impeller during an operation of the centrifugal pump to drive the pump portion and pump the low temperature fluid, the first rotation axis coaxial with the second rotation axis, insulating jacket means for thermally insulating at least the motor portion, the insulating jacket means surrounding at least the motor portion, at least a first vacuum jacket in the insulating jacket means, the first vacuum jacket including at least a low pressure vacuum between a motor outer surface and an inner surface of the first vacuum jacket, whereby tight contact between the insulating jacket means and the motor portion and coaxial alignment provides increased thermal efficiency, reduced size, and simplified construction, a pot, the pot sealed around a lower portion of the pump portion, the pot solely receiving the low temperature fluid during the operation, an intake pipe in the lower portion extending away the pump portion along the first rotation axis into the pot, the intake pipe and the impeller in fluid communication, the intake pipe and the impeller transporting the low temperature fluid from the pot during the operation and restricting direct contact of the low temperature fluid to the pump portion thereby providing a reduced pump surface area and an improved startability, a release pipe, the release pipe in sealed communication between the motor portion and an external portion of the centrifugal pump, the release pipe providing an release of any of the low temperature fluid and a vapor of the low temperature fluid which has improperly entered the motor portion, a vent pipe, the vent pipe in vapor communication between the pot and the release pipe, and at least a first portion of the vent pipe is located within the first vacuum jacket, whereby the first vacuum jacket provides easy double-service thermal insulation of the motor portion and the vent pipe.
According to another embodiment of the present invention there is provided a centrifugal pump, for pumping a low temperature fluid, comprising: a pump portion, a motor portion on the pump portion, an impeller in the pump portion, a motor in the motor portion driving the impeller during an operation of the centrifugal pump and pumping the low temperature fluid, the motor portion is coaxial with the impeller, a heat insulating jacket on the centrifugal pump, and the heat insulating jacket including a first insulating portion in tight contact around the motor portion, thereby reducing the centrifugal pump in size while increasing thermal efficiency.
The above, and other objects, features, and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.